A cryogenic treatment method for cemented carbide for cold heading dies

A cryogenic treatment and cemented carbide technology, which is applied in the production process of cemented carbide cold heading dies, can solve the problems of unfavorable stress elimination and no tempering process, so as to eliminate tensile stress, improve comprehensive performance and prolong service life. Effect

Active Publication Date: 2017-06-16
ZHUZHOU HARD ALLOY GRP CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The existing cryogenic treatment methods for cemented carbide use one step to directly cool down to the cryogenic treatment temperature, and then return to room temperature after heat preservation, but there is no tempering process, which is very unfavorable to the elimination of stress

Method used

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  • A cryogenic treatment method for cemented carbide for cold heading dies
  • A cryogenic treatment method for cemented carbide for cold heading dies

Examples

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Effect test

Embodiment 1

[0017] A cryogenic treatment method for a YG20 cold heading die with a cobalt content of 20%, the operation steps are: (1) putting the sintered cold heading die into a cryogenic treatment furnace; Liquid nitrogen, lowered to -80°C at a rate of -2°C / min, and kept for 1 hour; (3) lowered to -140°C at a rate of -1.5°C / min, kept for 2 hours; (4) kept at a rate of -1°C / min Lower it to -186°C, keep it warm for 4 hours, then cut off the power, and take it out after naturally heating up to room temperature; Raise the temperature to 100°C, keep it warm for 1 hour, then raise the temperature to 180°C at 1.5°C / min, keep it warm for 2 hours, then turn off the power, and let it cool down to room temperature naturally.

[0018] attached by figure 1 It can be seen that the microstructure of YG20 did not change significantly before and after cryogenic treatment. attached by figure 2 It can be seen that, compared with before cryogenic treatment, the face-centered cubic cobalt (fcc) in YG20...

Embodiment 2

[0021] A kind of cobalt content is the cryogenic treatment method of the MB50A cold heading mold of 22%, and its operation steps are: (1) the cold heading mold that sinters is put into the cryogenic treatment furnace; (2) open the cryogenic treatment furnace, pass into Liquid nitrogen, lowered to -75°C at a rate of -1.5°C / min, and kept for 2 hours; (3) lowered to -135°C at a rate of -1°C / min, kept for 4 hours; (4) kept at a rate of -1°C / min Lower it to -190°C, keep it warm for 5 hours, then turn off the power, and take it out after naturally heating up to room temperature; Raise the temperature to 95°C, keep it warm for 2 hours, then raise the temperature to 220°C at 1°C / min, keep it warm for 2 hours, then turn off the power and let it cool down to room temperature naturally.

[0022] Cold-heading Φ4.8 carbon steel screw straight rods with cold heading dies without cryogenic treatment and after cryogenic treatment, the results show that cryogenic treatment can increase the ser...

Embodiment 3

[0024] A kind of cobalt content is the cryogenic treatment method of MB65 cold heading die of 25%, and its operation steps are: (1) the cold heading die that sinters is put into cryogenic treatment furnace; (2) open cryogenic treatment furnace, pass into Liquid nitrogen, lowered to -85°C at a rate of -1°C / min, and kept for 2 hours; (3) lowered to -145°C at a rate of -0.5°C / min, kept for 4 hours; (4) kept at a rate of -0.5°C / min Lower it to -196°C, keep it warm for 6 hours, then cut off the power, and take it out after naturally heating up to room temperature; Raise the temperature to 105°C, keep it warm for 2 hours, then raise the temperature to 240°C at 0.5°C / min, keep it warm for 4 hours, then turn off the power and let it cool down to room temperature naturally.

[0025] The MB65 cold heading die without cryogenic treatment and after cryogenic treatment were cold-headed Φ8 stainless steel screw shrink rods, and the results showed that cryogenic treatment increased the servi...

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Abstract

The invention relates to a subzero treatment method of a hard alloy for a cold heading mold. Subzero treatment and tempering treatment are performed in sequence for the sintered hard alloy for the cold heading mold; the subzero treatment comprises the following three stages of cooling and insulation treatment after cooling: the temperature is firstly reduced to -75 to -85 DEG C, then is reduced to -135 to -145 DEG C, and is finally reduced to -186 to -196 DEG C; and the tempering treatment comprises the following two stages of heating and insulation treatment after heating: the temperature is firstly heated up to 95-105 DEG C, and then is heated up to 180-240 DEG C. The method enables part face-centered cubic (fcc) cobalt in the alloy to be converted to hexagonal close-packed (hcp) cobalt, improves the wear resistance and the comprehensive performance of the alloy, eliminates the tensile stress in the alloy, and prolongs the service life.

Description

technical field [0001] The invention relates to a production process of a hard alloy cold heading die, in particular to a cryogenic treatment method for a hard alloy cold heading die. Background technique [0002] Cemented carbide cold heading dies are often used for cold heading, cold punching and upsetting of metal materials. They bear a large impact force during work, the impact frequency is very high, and they have a certain working temperature. The use environment is very harsh, which requires cold Upsetting dies have both good impact toughness and certain wear resistance. [0003] At present, in order to improve the toughness of cold heading dies, alloys with high cobalt content (mass fraction is about 20%) are generally used in production. However, the thermal expansion coefficients of WC and Co are very different, and the interior of the alloy will be lower than that of cobalt during the cooling process. The alloy produces greater tensile stress, which makes the col...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22F1/16
Inventor 尹超颜练武任跃赵玉玲
Owner ZHUZHOU HARD ALLOY GRP CO LTD
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